Molecular Evidence for the Early Evolution of Photosynthesis

Abstract

The origin and evolution of photosynthesis have long remained enigmatic due to a lack of sequence information of photosynthesis genes across the entire photosynthetic domain. To probe early evolutionary history of photosynthesis, we obtained new sequence information of a number of photosynthesis genes from the green sulfur bacterium Chlorobium tepidum and the green nonsulfur bacterium Chloroflexus aurantiacus. A total of 31 open reading frames that encode enzymes involved in bacteriochlorophyll/porphyrin biosynthesis, carotenoid biosynthesis, and photosynthetic electron transfer were identified in about 100 kilobase pairs of genomic sequence. Phylogenetic analyses of multiple magnesium-tetrapyrrole biosynthesis genes using a combination of distance, maximum parsimony, and maximum likelihood methods indicate that heliobacteria are closest to the last common ancestor of all oxygenic photosynthetic lineages and that green sulfur bacteria and green nonsulfur bacteria are each other's closest relatives. Parsimony and distance analyses further identify purple bacteria as the earliest emerging photosynthetic lineage. These results challenge previous conclusions based on 16S ribosomal RNA and Hsp60/Hsp70 analyses that green nonsulfur bacteria or heliobacteria are the earliest phototrophs. The overall consensus of our phylogenetic analysis, that bacteriochlorophyll biosynthesis evolved before chlorophyll biosynthesis, also argues against the long-held Granick hypothesis.

Overall energy conversion efficiency of a photosynthetic vesicle

“…Evolutionary pressure toward greater fitness at the organism level results in the composition and architecture of photosynthetic systems to display adaptation toward optimal function (Xiong et al, 2000;Ş ener and Schulten, 2008;Blankenship, 2014). Such adaptation has been reported for the individual protein level; it is not as well understood at the system integration level.…”

“…These organisms absorb sunlight and subsequently utilize the Fö rster mechanism and quantum coherence (Strümpfer et al, 2012;Panitchayangkoon et al, 2010;Scholes, 2010) for efficient excitation energy transfer, followed by conversion of light energy into chemical energy (Feniouk and Junge, 2009). The light harvesting system of purple bacteria (Hu et al, 2002;Cartron et al, 2014) is claimed to be the earliest of the current photosynthetic lineages (Xiong et al, 2000) and exhibits, at the supra-molecular level as well as at the level of individual proteins, less complexity than the thylakoid membranes of the more ubiquitous cyanobacteria and plants (Kirchhoff et al, 2002).…”

Regulatory factors for the assembly of thylakoid membrane protein complexes

“…Thylakoids are flattened vesicles found in cyanobacteria and chloroplasts that probably arose in photosynthetic bacteria, appearing in close correlation with oxygenic photosynthesis [1]. The most advanced and efficient thylakoids are present in the chloroplasts of land plants, in which they are arranged into extensive, highly interconnected networks of grana stacks connected by stroma lamellae [2].…”

La vida temprana en la Tierra y los primeros ecosistemas terrestres

“…A pesar de que muchos detalles de la evolución de las cianobacterias no están resueltos, su capacidad de sintetizar clorofila a para absorber energías fotónicas más altas que otras bacterioclorofilas (Xiong et al, 2000), puede deberse a una presión selectiva para usar tales longitudes de onda que alcanzaban la superficie Precámbrica donde las cianobacterias tenían que vivir, contrario a las bacterias fototróficas púrpuras o verdes que utilizan menores longitudes de onda en sus hábitats sumergidos y protegidos. Así, desde una perspectiva multi-angular, las cianobacterias parecen ser organismos bien adaptados para la colonización de las primeras superficies terrestres.…”